Evidence Library
The Science
This is the peer-reviewed and expert evidence behind our campaign, drawn from medical journals and institutions like the American Academy of Pediatrics, the OECD, the WHO, and UNESCO. Taken together, it makes a clear case: for young children, heavy screen use carries real costs to health, sleep, development, and learning. We update this library as new research is published.
Mental Health
Teen anxiety, depression, and self-harm climbed sharply in the years screens and smartphones took over childhood. The research increasingly points to a connection, especially at heavy levels of use.
Humanities & Social Sciences Communications (Nature) · 2026
Four-plus hours of daily screen time linked to far higher depression and anxiety
A study of 50,231 U.S. children aged 6 to 17 found that four or more hours of daily screen time was associated with a 61 percent higher risk of depression and a 45 percent higher risk of anxiety, with sleep and exercise as the main pathways.
Clinical Psychological Science (Twenge et al.) · 2018
Depressive symptoms and suicide-related outcomes rose with screen time
Adolescents who spent more time on screens were more likely to report depressive symptoms and suicide-related outcomes, while those spending more time on non-screen activities reported fewer.
JAMA Psychiatry (Riehm et al.) · 2019
Heavy social media use linked to higher risk of internalizing problems
In a study of nearly 6,600 U.S. adolescents, those using social media more than three hours a day faced a higher risk of internalizing problems such as anxiety and depression.
Jonathan Haidt (Penguin Press) · 2024
The Anxious Generation: how the screen-based childhood drove a mental health crisis
Synthesizing a decade of data, Haidt argues that the rapid shift to phone- and screen-based childhood after 2010 is a major driver of rising adolescent anxiety and depression.
Sleep & Brain Development
For young children, the early years build the brain. The evidence shows screens crowd out sleep and are associated with measurable differences in development.
Sleep Medicine Reviews (Hale & Guan) · 2015
Screen time and sleep among school-aged children and adolescents
A systematic review found that in about 90 percent of studies, more screen time was associated with delayed bedtimes and shorter sleep duration in children and teens.
JAMA Pediatrics (Madigan et al.) · 2019
Screen time at 24 and 36 months predicts poorer developmental outcomes
A longitudinal study of nearly 2,500 children found that higher screen time in toddlerhood predicted weaker performance on developmental screening tests at later ages.
JAMA Pediatrics (Hutton et al.) · 2020
Screen use and brain white-matter integrity in preschool children
In children aged 3 to 5, higher screen use was associated with lower integrity of white-matter tracts that support language and emergent literacy skills.
Handwriting & the Brain
What children do with their hands shapes how they learn. A growing body of research shows that writing by hand builds the brain in ways typing on a screen does not.
Learning & Academic Performance
The promise was that more devices would mean more learning. The largest studies have not found that, and in several cases point the other way, especially for reading and focus.
OECD · 2015
Students, Computers and Learning: Making the Connection
Countries that invested heavily in classroom computers showed no appreciable improvement in student achievement in reading, math, or science.
Educational Research Review (Delgado et al.) · 2018
Reading comprehension is better on paper than on screens
A meta-analysis covering more than 170,000 readers found a consistent advantage for reading on paper over screens, growing stronger when reading was timed.
Psychological Science (Mueller & Oppenheimer) · 2014
The pen is mightier than the keyboard: longhand beats laptop notes
Students who took notes by hand understood material more deeply than those who typed on laptops, who tended to transcribe without processing.
UNESCO Global Education Monitoring Report · 2023
Technology in education: a tool on whose terms?
UNESCO warns that much classroom technology is adopted without evidence of benefit, and that the mere presence of a phone can pull students off task and lower learning.
Physical Health & Recommendations
Time on screens is time not spent moving, reading, or playing in person, and it shows up in children's bodies. More than 40 percent of U.S. children are now nearsighted, roughly double the rate of 50 years ago. Leading health bodies set clear, conservative limits for young children.
JAMA Network Open · 2025
Each added hour of daily screen time raises a child's odds of myopia
A meta-analysis of 34 studies and more than 314,000 people found each additional hour of daily screen time was linked to roughly 21 percent higher odds of nearsightedness, with risk climbing sharply between one and four hours a day.
European Spine Journal · 2025
Tech neck: the silent pandemic that is reshaping our spine
Researchers describe how the sustained forward head tilt typical of device use places heavy load on the spine. At a 45-degree tilt that load reaches roughly 49 pounds, and children accumulate well over 1,800 hours a year in this posture.
American Academy of Pediatrics (Pediatrics) · 2016
Media and Young Minds: AAP policy on screens for young children
The AAP recommends avoiding screen media other than video chat before 18 months and limiting use to about one hour a day of high-quality programming for ages 2 to 5.
World Health Organization · 2019
Guidelines on physical activity, sedentary behaviour and sleep for under-5s
The WHO advises no sedentary screen time for children under 1, none recommended for ages 1 to 2, and no more than one hour a day for ages 3 to 4.
Data Privacy
The devices and apps handed to our children also collect data about them. Independent investigations have raised serious concerns about how that information is gathered and used.
Human Rights Watch · 2022
How Dare They Peep into My Private Life: childrens data and ed-tech
An analysis of widely used education apps found that the majority surveilled or could surveil children, often harvesting data and sharing it with advertising technology companies.
Electronic Frontier Foundation · 2017
Spying on Students: school-issued devices and student privacy
The EFF documents how school-issued devices and ed-tech services collect detailed information on students, frequently without clear consent or transparency for families.